The photochemical properties of silicon octaphenoxyphthalocyanines (SiOPPc) oligomerized were studied in dimethylsulfoxide (DMSO) solutions. Oligomers containing 2-5 and 9 SiOPPc rings linked with terephthalate linkages were synthesized. Singlet oxygen quantum yields were found to be in the range 0.11-0.34, and increased with the number of rings up to five rings, a decrease in the quantum yield was observed for nine rings. This is explained in terms of the high aggregation of the oligomer containing nine rings.